At left, scientist Paul Dayton deploys an experiment in McMurdo Sound in the 1960s. At right, a "benthic grab" recovered from one of the lost experiment sites by Dayton and a team of divers in October 2010. The instrument's use dates back to the 1950s.

Historical artifact

Divers recover piece of lost experiment from 'dawn' of research in McMurdo Sound

By Peter Rejcek, Antarctic Sun Editor

Posted December 24, 2010

An artifact from the “dawn” of biological research in McMurdo Sound has been recovered from the seafloor and turned over to the Albert P. Crary Science and Engineering Research Center at McMurdo Station for display.

A team of research divers revisiting decades-old experiments that consisted of cages and other artificial structures — home now to all manner of marine organisms — retrieved the coral-encrusted “benthic grab” in October from the frigid waters beneath the sea ice.

A benthic grab is a heavy instrument that does pretty much what its name implies: Once dropped to the bottom, it bites into the seafloor and then brings up a sample of organisms that live on or just below the bed.

The particular instrument was first used by John Dearborn in 1958 during the International Geophysical Year when McMurdo Station was simply a naval air facility. A PhD student at Stanford University, Dearborn wintered over in 1959. He returned the next year with John Pearse, another benthic ecologist, and the two men continued their survey of McMurdo Sound into the winter of 1961.

“Historically, this grab was the most important single instrument for seafloor ecology in McMurdo Sound,” wrote Paul Dayton, a professor at Scripps Institution of Oceanography and another pioneering marine ecologist who made numerous dives in Antarctica from the 1960s to the 1980s.

The so-called lost experiments revisited by the research divers had been set up by Dayton and his colleagues during those previous decades. He returned to McMurdo Station this season for the first time in 20 years as a co-principal investigator on a project to track the changes in the seafloor ecosystem.

The benthic grab was lost in 1961, and it remained on the bottom of McMurdo Sound until anchor ice (ice attached to the ground) lifted off the seafloor and stuck into the bottom of the floating sea ice above.

That’s where Dayton found it in 1967. He used its weight to demonstrate the lifting power of anchor ice, and published the results form the experiment in a 1969 Science paper. He used it for several other experiments, eventually abandoning it in 1974 as a weight to sink another experiment.

“Of course, I now regret that abuse of such an historic artifact, and we retrieved it a couple weeks ago, encrusted but in remarkable shape,” Dayton said in an e-mail in late October.

The 69-year-old professor said both Dearborn and Pearse agreed that the artifact should remain at McMurdo Station.

The instrument’s value lies not in just its age, Dayton noted. He said Dearborn’s work relied heavily on its use from 1958-61. The research was the “most comprehensive bottom survey of any deep-water habitat in the world. [Dearborn] has fond memories of hauling the icy rope in the dark, in temperatures to 50 below.”

Dearborn, 77, died shortly after learning about the recovery of his key piece of equipment, on Nov. 22, 2010. He was an emeritus professor of marine sciences at the University of Maine, where he had worked from 1966-99.

Cara Sucher, manager of the Crary Lab, said she plans to build or purchase a pedestal to display the benthic grabber in the building’s main hallway. Dayton offered to clean up the crusty instrument — about the size of a small boat anchor — but Sucher argued it was perfect just the way it was found – crust, rope and all.